The number of anti-depressant prescriptions has risen by nearly 7% in a year, an investigation has found.

Between October 2015 and September 2016, the number of prescriptions went up from 59.5 million to nearly 63.6 million, according to latest figures from NHS Digital revealed to the BBC's 5 live Investigates team.

The four million rise equates to a record £780,000 a day spent on anti-depressants by the NHS - £285 million a year, the investigation found.

NHS Digital statistics for each year show that anti-depressant prescriptions have risen more than four fold over 20 years.

In 1995, 13.2 million prescriptions were issued, while in 2015 the number had more than quadrupled to more than 61 million.

While the numbers do not necessarily mean the number of people using anti-depressants is increasing, people could be using them for longer.

Research from London's University College Hospital revealed that a quarter of users now take anti-depressants for around 15 months, compared to eight months 20 years ago.

Dr James Davies, a reader in social anthropology and mental health at the University of Roehampton, said people experiencing difficulty with withdrawal and a lack of alternative options could be behind the rise.

He told the Press Association: "P art of the increase is due to people remaining on the prescriptions for longer, and of course one of the reasons why we are seeing that happen is because people are finding it difficult to come off these medications, experiencing withdrawal effects.

"One of the things you find being spoken about again and again is the fact that when they experience these withdrawal symptoms, they are often being misinterpreted by their doctors as evidence that the original problem is recurring."

There is also a lack of provision for alternatives, with psychological therapy "patchy throughout the country" and months-long waiting lists, he added.

"Doctors' hands are tied: in the absence of having an alternative to offer they end up reaching for the prescription pad - this can account for partly why prescription rates are continuing to go up."

A Department of Health spokesman said: "A rise in the number of prescriptions does not necessarily mean a rise in the number of patients: more frequent prescriptions for a shorter period allow medication to be reviewed more often and can cut down wastage. This can be very helpful for some patients."

:: 5 live Investigates will be aired on Radio 5 on Sunday February 12 at 11am.